william la jeunesse joins us live from los angeles. william, what are you learning about this shooting? >> reporter: well, gregg, as you said, you've got deputies and agents, state and federal helicopters, the manhunt underway just north of naco, arizona. maybe a thousand people, mostly ranchers. it's about 100 miles southeast of tucson. the shooting occurred near state route 80 which connects to interstate 10 going east and west. that is why this is one of the most active drug-smuggling corridors in the u.s. consider the topography. you go from very flat desert immediately to about 10,000 feet of elevation. it's steep, rugged, hard to access forcing the border patrol to go on foot and horseback. now, we are told early this morning around 2 in the morning local time one of the thousands of sensors laid down by the border patrol went off. three agents responded. one agent on horseback was shot and killed, another airlifted to a nearby hospital with two gunshot wounds. he'll be fine. and a third agent was not hit. now, no id or age on th